The present invention relates to telephone equipment and in particular to an improved ring period detector circuit.
Telephone equipment, such as modems, commonly include circuits which provide automatic telephone answering options. These circuits utilize a ring signal detector to detect an incoming call and automatically respond in accordance with some preselected format.
Ring signals are generally in the 22.5 Hz to 55 Hz frequency range. A problem arises in that certain dial pulses are in the 10 Hz to 18 Hz frequency range and hence are sufficiently close in frequency to the ring signals that they may be confused as ring signals.
In view of the above, it is a principal object of the present invention to provide an improved ring signal detection circuit which can discriminate ring signals with a high degree of precision over other low frequency signals.
A further object is to provide such a circuit which utilizes conventional components and may readily and economically be implemented into other telephone system components.
Still further object will become apparent from the following description of the invention.